Along with the practical application of optical communication system in recent years, the system with large capacity, multiple functions and high speed has been required. For example, to generate optical signal with higher speed, to demultiplex/multiplex optical wavelengths in a same optical transmission line, and to add a new function such as switching/exchanging of optical transmission line are required.
Of them, especially optical waveguide elements, such as AWG (arrayed waveguide grating) that enables the demultiplexing/multiplexing of optical wavelengths, and a matrix switch that enables the switching of optical transmission line, have been actively developed. The input/output part of these optical waveguide elements are structured such that multiple optical waveguides are arranged at equal intervals, and, to facilitate the optical connection with optical transmission line such as an optical fiber, it employs a arrayed optical fiber connector.
FIG. 1 is a perspective view showing a conventional arrayed optical fiber connector. The arrayed optical fiber connector 10 is structured such that multiple (four, in this example) optical fibers 11a, 11b, 11c and 11d, each of which having a core 1 and a clad 2, are disposed in an alignment assembly 12.
The alignment assembly 12 is composed of a nearly rectangular-solid-shaped board 13 and a fixing plate 14 that has the same form as the board 13 except having a thickness less than the board 13.
The board 13 is provided with a rectangular-cross-sectional groove 13a that contains the optical fibers in alignment at its bottom. The groove 13a has a length that extends through between two sides orthogonal to its bottom, a depth that is nearly equal to the diameter of the optical fibers 11a to 11d, and a width that is equal to the sum of the diameters of the optical fibers 11a to 11d.
The method of assembling the arrayed optical fiber connector 10 thus composed is explained. First, the tips of the four optical fibers 11a to 11d are, side by side, inserted into the groove 13a provided on the board 13, and adhesive 15 is filled into the clearance between the groove 13a and the optical fibers 11a to 11d. Then, the fixing plate 14 is disposed on the surface where the groove 13a is formed of the board 13, brought in contact with the optical fibers 11a to 11d.
Then, by heating the board 13 to harden adhesive 15 while pressing the fixing plate 14, the board 13, the optical fibers 11a to 11d and the fixing plate 14 are integrally fixed, thereby obtaining the arrayed optical fiber connector 10.
The basic performance required to the arrayed optical fiber connector 10 is that the optical fibers 11a to 11d do not incur the positional deviation when the end face of the arrayed optical fiber connector 10 is polished and after it is connected with an optical waveguide element. If the optical fibers 11a to 11d incur the positional deviation, there occurs a deterioration in performance such as an increase in connection loss with optical wavelength element that causes a reduction in reliability of optical wavelength element.
However, in the conventional arrayed optical fiber connector 10, there is a problem that it is difficult to prevent the optical fibers 11a to 11d from incurring the positional deviation when the end face of the arrayed optical fiber connector 10 is polished and after it is connected with an optical waveguide element.
FIG. 2 is a plan view illustrating the problem of the conventional arrayed optical fiber connector.
As shown, due to the low precision in processing the groove 13a, the board 13 used for the arrayed optical fiber connector 10 has been manufactured such that the bottom of the groove 13a is declined comparing with the upper surface of the board 13. In this case, even when, like the above method, the optical fibers 11a to 11d and the fixing plate 14 are integrally fixed while using the board 13 thus manufactured, the fixing plate 14 does not contact all the optical fibers 11a to 11d since the bottom of the groove 13a is declined. As a result, clearances da, db, dc and dd must occur between the fixing plate 14 and the optical fibers 11a to 11d.
Thus, the fixing force between the fixing plate 14 and the optical fibers 11a to 11d is reduced, and the optical fibers 11a to 11d each are likely to incur the positional deviation according to the clearances da, db, dc and dd when the end face of the arrayed optical fiber connector 10 is polished and after it is connected with an optical waveguide element. Because of this, it is difficult to perfectly prevent the positional deviation.